Contact Potential Difference Measurements by the Kelvin Method

Measurements of contact potential differences between clean metallic surfaces produced by condensation from the vapour, by the vibrating condenser modification of the Kelvin method, yield the following values for average work functions, on the basis of an assumed value of 4.565 ± 0.025 eV for the work function of tungsten: copper, 4.52 ± 0.04 eV; silver, 4.31 ± 0.03 eV; gold, 4.70 ± 0.03 eV, aluminium, 4.20 ± 0.05 eV; nickel, 4.74 ± 0.04 eV; molybdenum, 4.22 ± 0.05 eV; iron, 4.17 ± 0.03 eV. The lack of contamination and the reproducibility of results are attributed to the use of molybdenum gettering films, and to the outgassing procedures employed.